Читать книгу The Gun Digest Book of .22 Rimfire. Rifles·Pistols·Ammunition онлайн

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Even with the use of smokeless powder, the problem of corrosion persisted. The cause was the residue that was produced from the primer that was a mixture that contained potassium chlorate. Because of the resulting corrosion, primers containing potassium chlorate became known as corrosive primers. Some ammunition was loaded with primers containing mercury fulminate and after detonation the resulting mercury reacted with the brass case which caused it to be weakened and thus unsuitable for reloading. In 1927, Remington introduced Kleanbore primers that contained a type of priming mixture that was noncorrosive. In most modern ammunition, the primer contains an explosive known as lead styphnate, but recently primers have been developed that do not contain lead. The motivation behind this is to reduce the amount of lead that is present in the air when firearms are used on indoor ranges. For use in rimfire cartridges, the priming mixture contains 35 to 45 percent lead styphnate, 25 to 35 percent barium nitrate, 18 to 22 pecent ground glass, and 6 to 10 percent lead thiocyanate as well as some other minor constituents. The function of the ground glass is to make the mixture more sensitive to friction when crushed in the rim. On the negative side, the small amount of ground glass remaining in the bore increases the rate of wear so that even though soft lead bullets are used, the bore eventually shows the effects of erosion. A 22 LR barrel will not last indefinitely. One of the characteristics of lead styphnate is that its explosive character is destroyed by oil and some organic solvents. If oil seeps into a case, it may cause the round to misfire. This is one reason for the substantial crimp given to 22 rimfire ammunition, the other being that a heavy crimp is necessary to give the correct “pull” that results in uniform velocities.